gtk3: replace colorsel sample by GTK+ 3 sample
gtk3: replace colorsel sample by GTK+ 3 sample

see: https://git.gnome.org/browse/gtk+/tree/demos/gtk-demo/colorsel.c

kitachro/ruby-gnome2,kitachro/ruby-gnome2,kitachro/ruby-gnome2,kitachro/ruby-gnome2,kitachro/ruby-gnome2